Evaporator apparatus



Oct. 3, 1950 J. P. RATHBUN EVAPORATOR APPARATUS 3 Sheets-Sheet 1 Filed Aug. 18, 1947 Vllllllllllll 4 INVENT-OR' WT xw ATTORNEY Oct. 3, 1950 J. P. RATHBUN EVAPORATOR APPARATUS 3 Sheets-Sheet 2 Filed Aug. 18, 1947 INVENTOR JZELZ'L P Eafl/ ztzz wrmasszs; f- 64?- ATTORNEY Oct. 3, 1950 RATHBUN 2,524,715

EVAPORATOR APPARATUS Filed Aug. 18, 1947 3 Sheets-Sheet 3 WITNESSES: INVENTOR *7- JZ/m PPAAUR ATTORNEY patented Got. 3, 1950 EVAPORATOR APPARATUS John 1. Rathbun, Prospect Park, Pa, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa.,-a corporation of Pennsylvania Application August 18, 1947, Serial No. 769,131 3 Claims. (Cl. 122 -379) The invention relates to evaporators of the tubular type and it has for an object to improve operation of .apparatusof this character from the point of view of removal of scale and refuse from the exterior of the tubes.

The aforesaid objective is obtained by keeping the tubes of the bundle spaced without thereby imposing constrain-t thereon, by the use of means for spacing the-tubes while providing for complete freedom of movement for bowing thereof in a single direction to crack and aid in the removal of scale, :and by the provision of means affording a slidable mounting for the tube bundle and the tube spacing means together with steam, discharge, and vent connections having joints readily accessible through a hand hole :at the closed end of the shell and through the open end of the latter when the cover is removed.

By keeping the tubesproperly spaced, vertical tube lanes are preserved for scale to drop through the bundle into the-bottom portion of the shell for removal by blowing down the unit. While support. plates have heretofore been used for spacing the tubes, such plates have been positioned or supported by means causing the plate to. interfere with freedom of the tubes to bow with the result that, thermal expansion of the tubes has resulted in the latter becoming distorted or displaced. In accordance with the present invention, the tube support plate is positioned by collars carried by at least three tubes at the top and bottom of the nest and arranged in close proximity to opposite sides of the support plate, whereby the latter is held substantially in a verticalplane while allowing for complete freedom of movement for bowing with maintenance of proper spacing of the tubes.

By having the tubebundle slidably mounted in the shell with steamfvent and-discharge-connections readily uncoupled through access afforded at the ends of the shell, the bundle may be readily withdrawn to the extent required for removal of scale and debris not removed by the periodic procedure of heating and cooling the tubes to cause the latter to bow and straighten for descaling followed by flushing or blowing down for the removal of released scale and refuse. Accordingly, the bundle is carried by skids or rails arranged at'opposite sides of the lower portion of the shell; and,as the support plate is arranged to bear on the rails or skids, with the tubes having a slight amount of upward bow when cold, the skids or rails fix the minimum extent of bowing without interfering with freedom of the tubes to bow in a single direction and without interfering with the freedom of the bundle and the tube support plate to be withdrawn by sliding thereof along the skids.

By having the guide rails formed with a pair of opposed vertical faces and the tube support plate with a portion fitting between the faces, the support plate is centered vertically with respect to the shell. Therefore, a more particular object of the invention is to provide the tube nest of .B, tube bundle with a support plate carried by at least three tubes arranged at the top and bottom of the nest and which support plate maintains the tubes in spaced relation to provide lanes through which scale and refuse are free to pass into the lower portion of the shell.

Another object of the invention is to provide, with a tube bundle having a nest of tubes arranged to bow in response to thermal expansion to aid in scale removal, a support plate carried by at least three tubes at the top and bottom of the nest so that the support plate is free to move with the nest without imposing restraint on the tubes to bow in a single direction and with preservation at all times of the tube spacing providing vertical lanes through which scale may drop to the bottom portion of the shell.

A further object ofthe invention is to provide a tube bundle slidably mounted on rails or skids andhaving steam, vent and drainage connections capable of being connected and disconnected through a hand hole at the closed end of the shell and through the open end of the latter when the cover is removed together with a tube support plate for spacing of the tubes and which is positioned by the latter so that it is free to movewith the tubes, thereby permitting the latter to bow freely in the same direction, the tube plate being arranged to bear on the rails or skids when the tubes are. bowed to the minimum extent, whereby the support plate at all times spaces the tubes and is slidable along the skids or guides with the bundle when the latter is assembled and removed with respect to the shell.

The foregoing and other objects are effected by the invention as will be apparent from the following description'and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Figure 2 is a sectional view taken along the line II-II of Figure 1;

Figure 3 is a sectional view taken along the line III-III of Figure 1;

Figure 4 is a sectional detail view of collars carried b a tube for positioning the support plate;

Figure 5 is a detail view of one of the collars;

Figure 6 is a detail view showing a portion of the drainage connection for the discharge header;

Figure 7 is a diagrammatic view; and

Figure 8 is an isometric view showing the tube bundle partially removed from the shell.

In the drawing, there is shown an evaporator comprising a shell, at I0, having a tube bundle, at ll, therein. Water, supplied by conduit 12 to the interior of the shell, is vaporized by heating fluid, for example, steam, supplied to the tubes of the bundle by a conduit [4. Vapors are discharged from the shell through the outlet l5 including the separator IS.

The shell comprises a cylindrical body I! having one end closed by a unitary end wall l8 and having its other end closed by a detachable cover IS.

The tube bundle, at H, comprises an inlet header located adjacent to the cover IS, a discharge header 2| located adjacent to said end wall 18, and a nest of tubes 24 having their ends rolled into the tube plates 25 and 26 of the inlet and discharge headers.

Before attachment to the tube plates, the tubes are prebent, as indicated in diagrammatic Figure 7, and they are attached to the tube plates so that they all how upwardly.

The shell body has interior rails 21, 21 in the lower portion thereof and the headers have slidable bearing relation with respect thereto, the discharge header 2| bearing directly on the rails or skids and the inlet header have dependent feet 28, 28 which bear on the rails, whereby the inlet header is elevated relative to the discharge header to provide for downward inclination of the tubes toward the discharge header.

A tube support plate 30 extends transversely of the tube nest and it has openings 31 through which the tubes pass. The support plate is held in position relative to the nest to keep the tubes in spaced relation, by means of pairs of collars 33, 33 attached to three or more tubes at the top and bottom of the nest with each pair of collars in proximity to opposite sides of the support plate 30. As shown in Figure 3, such collars are carried by a pair of tubes at or near the top of the nest and at the sides of the latter and by a pair of tubes at or near the bottom of the nest and at the sides of the latter, such tubes being designated 24a.

While the drawing shows one support plate 30, it is to be understood that the number thereof depends on the tube length. The unsupported tube span length should not exceed about tube diameters.

Manifolds 3,3, 33 in the upper portion of the shell and at the sides of the latter discharge oppositely directed and staggered water sprays from the nozzles 34 forming a spray curtain between the top of the bundle and the vapor outlet I5. Normally, water supplied thru the nozzles is sufficient to maintain a body thereof just about submerging the tubes, the normal maximum water level being indicated by the dash line aa in Figure 1, whereby the tubes are effective to deliver heat to the water to vaporize the latter.

The shell has one or more drainage or blow- 13';

down outlets 35 at the bottom thereof and each outlet has a valve 36. With such valve or valves closed, continued vaporization of water from the submerging body thereof results in increased solids concentration. While the solids concentration may be limited by periodic dumping of the body of liquid in the shell followed by the renewal of such body, I prefer to adjust the valve or valves 36 to provide for continuous drainage or blowdown of water from the shell, thereby providing for a continuous supply of water to the body and removal of water therefrom to limit the solids concentration.

Vapors released from the body of liquid and passing upwardly enter the water curtain, with the concentration of the body from which it is released and it leaves the curtain for discharge from the outlet ['5, with the concentration of the incoming feed water supplied through the nozzles 34.

Preferably, the inlet and discharge headers are connected by tie bars or rods 31 so that the tubes 24 may be caused to bow and straighten due to increase and decrease in temperature to aid in scale removal. Preferably, the tubes are also prebent, as indicated in Figure 7, and rolled into the tube plates 25 and 26 of the headers so that, when cold, such tubes having an initial upward bow in a vertical plane with the support plate carried by the tubes and bearing on the guide rails 2'1, 21. With thermal expansion of the tubes, the latter are free to bow, the support plate 30 moving upwardly with the tubes, it being held substantially in a vertical plane by the collars 33, 33 attached to the upper and lower pairs of tubes 24a so as to allow complete freedom of movement for bowing in a vertical plane while maintaining proper spacing of the tubes of the nest. The guide rails 21, 21 have opposed vertical faces 38, 38 cooperating with the depending portion 38a of the support plate, whereby the latter is guided vertically or centered vertically with respect to the shell.

The connection 14 supplies steam to the inlet header 20, a vent connection 39 provides for venting of the upper portion of the discharge header, a drainage connection 40 provides for draining of water of condensation from the discharge header, and the conduit I2 supplies water to the manifold pipes 33, 33. The drainage or discharge conduit 40 extends longitudinally at the bottom of the shell and it includes an expansion section 4| accommodating for change in length of the conduit due to temperature changes. The conduit 40 extends along the interior of the shell and has a portion 42 extending outwardly through the shell near the cover IQ. To avoid interference of the depending portion 38a of the support plate with the conduit, such depending portion is notched as shown at 43.

The end wall l8 of the shell has a hand hole 44 provided with a cover 45. Aside from the location of a joint 46 in the water conduit Hi to be accessible through the hand hole 44, the provision of a joint 41 in the vent connection and accessible through the hand hole 44, and provision of joints 48 and 49 in the steam and drainage connections and accessible through the open end of the shell when the cover is removed provide.

for ready removal of the tube bundle, the latter then being freely slidable along the skids or rails 21, 21. As the tube support plate 30 normally bears on the rails when the tubes are cold and slightly bent upwardly due to the prebent deforsupport plate is freely slidable along the rails and does not in any way interfere with freedom of the tube bundle to be slid outwardly along the rails. Furthermore, the rails function as means cooperating with the tube support plate to fix the lcwest position thereof or the minimum extent of bowing of the tubes when the latter are cold.

In operation, vapor released by a body of liquid within theevaporator and having the salt concentration of such liquid passes upwardly through the water curtain and leaves the latter with the concentration of the entering feed water. At periodic intervals, the tube bundleis subjected to alternate heating and cooling effects to cause the tubes to bow and straighten for the purpose of cracking and exfoliating scale; and, as the tube support plate spaces the tubesand keeps all of the latter bent or. bowed in the same direction, preservation of lanes forpassage of released material to the lower portion ofthe shell is assured. As suming that water is drained from the shell and the supply through the conduit I2 is interrupted, if steam supplied to the inlet header, the tubes will be heated and to an extent dependent upon the heating. On the other hand, interruption of the steam supply and'restoration of the water supply to the manifolds 33, 33, bring about rapid cooling of the tubes to straighten or diminish the bowing of the latter. The alternate bowing and straightening operations provide for cracking off of scale, release of scale being facilitated by heating for the reason that water which may have percolated through a crack may be vaporized and set up pressure effective to peel off scale particles. During this procedure of alternate bowing and straightening effected by heating and cooling, the support plate assures of the tubes being maintained in proper spaced relation and direction of bowing, whereby vertical lanes between the tubesare preserved for the passage of scale through the nest to the interior of the shell at the bottom. After removal of scale in this way, the accumulation thereof may be flushed out or blown down from the shell. To this end, water is supplied through the connection 5! to the cone duits 52 shown as being constituted by the rails 2? and the shell, the conduits 52 being cross connected by a pipe 53 so that water entering the inlet 5! is supplied to both conduits, and being discharged through nozzle openings 54 in the guide rail vertical for agitation of medium in the 1. In an evaporator, a horizontal shell, an end wall unitary with said shell and closing one end thereof, and a detachable cover closing the other end of said shell; said shell having a normally,- closed blow-down opening at its bottom; a pair of rails attached to the interior ofthe shell in the lower portion thereof; a tube bundle including inlet and discharge headers, tie means connecting the headers, and upwardly-bowed tubes having their ends attached to the headers; said headers having slidable bearing relation with respect to said rails and being arranged so that the tubes are inclined downwardly from the inlet header to the discharge header; the inlet header being adjacent said cover and discharge header being adjacent said end wall; means including nozzles for discharging a curtain of sprayed water above the bundle; a vent connection for the upper portion of the discharge header and extending through thewall of the shell at the end of the latter adj acent to, said end Wall; a discharge conduit connected to the bottom of the discharge header and having a portion extending through the wall of the shell body at the end thereof adjacent to said cover; a steam conduit extending through the wall of the shell and connected to the inlet header; said end wall having a hand hole; a cover for the hand hole; a joint in the vent connection accessible through the hand hole when the cover of the latter is removed; joints for the steam conlower portion of the shell incident to flushing out or discharge thereof, as disclosed and claimed in the application of Charles P. Ludman, et al., Serial No. 769,200, filed August 18, 1947, Patent No. 2,504,710, patented April 18, 1950.

While the periodic descaling operation described is suflicient for day-to-day operation, as scale and refuse may accumulate on the nest of tubes and for which the bowing and straightening operations are inadequate to effect removal.

Therefore, in addition, the tube bundle is supported for ready withdrawal, the steam, vent and; drainage connections having couplings accessible from the ends of the shell and facilitating this result. The tube support plate not only serves the purposes already indicated but it bears on the rails providing for withdrawal of the bundle so that the rails fix the lowest position to which the tubes may be straightened by cooling; and, as the support plate merely bears on the rails, it is, not only free to move upwardly without imposing restraint on freedom of the tubes to bow, but it does not interfere with the tube bundle being freely withdrawn from the shell.

duit and for said portion of the discharge conduit and which joints are accessible from the open end of the shell body when said first-mentioned cover is removed; a tube support plate carried by the tubes between the headers and having openings through which the tubes pass; means carried by a plurality of said tubes at opposite sides of the support plate to hold the latter upright without imposing any restraint to vertical bowing of the tubes; said rails having parallel and opposed vertical surfaces; and a portion depending from the plate and guided by said surfaces.

2. In an evaporator, a horizontal shell having a detachable cover at one end; a pair of spaced rails attached to the interior of the shell body in the lower portion thereof; a tube bundle including inlet and :discharge headers, tie means connecting the headers, and upwardly-bowed tubes having their ends attached to the headers; said headers having slidable bearing relation with respect to said rails and being arranged so that the tubes are inclined downwardly from the inlet header to the discharge header; the inlet header being adjacent said cover and discharge header being adjacent said end wall; a tube support plate arranged between the headers, extending transversely of the nest of tubes, having openings through which the tubes pass, and bearing on said rails when cold; mean for maintaining the position of the support plate relative to the tubes so that the support plate is effective to keep the tubes in spaced relation; said last-named means comprising pairs of collars attached to three or more tubes at opposite sides of the plate; the collars of each pair being attached to its tube in proximity to opposite sides of the support plate; and means including said rails and a depending portion of said support plate for maintaining the support plate centered vertically with respect to the shell.

3. In an evaporator; a horizontal shell; a unitary tube bundle supported interiorly of the shell by the latter; said tube bundle including inlet and discharge headers, tie means connecting the headers, and upwardly-bowed tubes having their ends connected to the headers; a tube support plate arranged between the headers and having openings through which the tubes pass so that the plate is carried by the latter and moves therewith as the tubes undergo bowing changes due to temperature changes; means carried by a plurality of tubes for confining the plate relative to such tubes in opposite directions longitudinally of the latter to maintain the plate in upright position without imposing any restraint to vertical bowing of the tubes; and means carried by the shell and cooperating with the plate to guide the latter vertically so that bowing movement of each tube is confined to a vertical direction.

JOHN P. RATHBUN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,018,489 Graf Feb. 27, 1912 1,304,496 MacLachlan May 20, 1919 1,617,081 Price Feb, 8, 1927 FOREIGN PATENTS Number Country Date 335,911 Great Britain Sept. 30, 1930 

